I had my water tested and no worries. I also run a whole house filter and a RO filter for drinking water.
I live in a place built right after WWII and it has an airlift well similar to yours. It's never had any problem since it was drilled, other than the replacement of the compressor and water pump. My cistern is made of concrete. When we moved in, the compressor was still here, but somebody lifted the pump and all the copper connected to the well-house. but we put a new motor on the compressor, installed a new pump and pressure tank, along with all new PVC, and then after disinfecting every part of the existing cistern and well, fired it up and away she went
Water tests continue to come up clean and good. My compressor doesn't have a tank below it though. It does have a very long stroke and a two piston setup. I guess that was how they got the volume out of them back them. A lot of people scoff or make fun of these, but back in the day before submersible pumps, this was the COMMON way to get water from deep. There are still thousands of them around, reliably doing their job day after day. No moving parts down-hole makes a pretty solid setup.
Either way, we never had any oil in the water as others have said here. From what I have heard, you have to move a colossal amount of CFM's before you blow much oil down into the well. We have a filter in-line just in case though. Don't worry about your well too much
if it's done right it will run for years and years and years
You might have to change a compressor belt from time to time, but even that runs well near forever if it's all aligned right. Do get a shelter over it PDQ though. Your equipment will thank you. PVC also doesn't really like UV much.
Good to meet you by the way.